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| 1.
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岩田, 佳雄 ; 小松﨑, 俊彦 ; 浅沼, 春彦 ; 北山, 弘樹 ; Iwata, Yoshio ; Komatsuzaki, Toshihiko ; Asanuma, Haruhiko ; Kitayama, Hiroki
概要:
金沢大学理工研究域フロンティア工学系<br />If damping alloy is used as structural material, a structure with high damping performance can b
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e produced and its vibration and noise can be reduced. Damping mechanism of the damping alloy is to convert vibration energy into thermal energy. The damping performance of the damping alloy is not as good as it is used in a dynamic damper. This paper proposes a method of enlarging equivalent loss factor of a damping alloy spring by using a negative spring constant and it is confirmed that the equivalent loss factor of a damping alloy cantilever becomes large by the attraction force of magnet used as the negative spring constant. Optimal design of the dynamic damper which consists of the damping alloy cantilever and a pair of magnets is explained. The vibration suppression effect due to the dynamic damper is demonstrated by means of measuring the compliance and the time history response by impact excitation. The vibration suppression effect depends on the vibrational amplitude due to nonlinearity of the attraction force of magnet but can be sufficiently expected in comparison with the case without the dynamic damper.
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| 2.
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Nguyen, Xuan Bao ; Komatsuzaki, Toshihiko ; Iwata, Yoshio ; Asanuma, Haruhiko ; 小松崎, 俊彦 ; 岩田, 佳雄 ; 浅沼, 春彦
概要:
金沢大学理工研究域機械工学系<br />In this paper, a magnetorheological elastomer (MRE) based isolator was investigated to mitigate exce
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ssive vibrations in structures during seismic events. The primary objectives of this research are to propose a numerical model that expresses viscoelastic behaviors of the MRE and predict operation process of the MRE-based isolator for future design of isolator systems for various technical applications. Despite the simplicity in parameter definition in comparison to the conventional models, the proposed model works efficiently in a wide range of frequencies and amplitudes. The model consists of the following components: viscoelasticity of host MRE, magnetic field-induced property, nominal viscosity as well as high stiffness in low excitation frequency that are modeled in analogy with a standard linear solid model (Zener model), a stiffness variable spring, and a smooth Coulomb friction, respectively. Furthermore, a semi-active fuzzy controller was designed to enhance the performance of the isolator in suppressing structural vibrations. The control strategy was built to determine the command applied current. The controller is completely adequate for handling the nonlinearity of the isolator and works independently with the building structure. The efficiency of the MRE-based isolator was evaluated by the responses of the scaled building under seismic excitation. Numerical and experimental results show that the isolator accompanied with a fuzzy controller remarkably reduces the relative displacement and absolute acceleration of the scaled building compared to passive-off and passive-on cases. © 2017 Elsevier Ltd<br />Embargo Period 12 months
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| 3.
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小松﨑, 俊彦 ; Komatsuzaki, Toshihiko
概要:
取得学位：博士(工学)，学位授与番号：博乙第275号，学位授与年月日：平成16年3月25日,学位授与年：2004
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Komatsuzaki, Toshihiko ; Iwata, Yoshio ; Morishita, Shin
概要:
In the present study, acoustic wave propagation in the field including sound isolation panel is simulated using Cellular
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Automata (CA). CA is a discrete system which consists of finite state variables, arranged on a uniform grid. CA dynamics is described by a local interaction rule which is used for computation of new state of each cell from the present state at every time step. In this study a sound field is modeled using CA where the sound isolation panel exists and the numerical simulation results are evaluated quantitatively by the insertion loss. The results showed good correspondence with analytical solutions. © 2012 Springer-Verlag Berlin Heidelberg.
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| 5.
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Komatsuzaki, Toshihiko ; Inoue, Toshio ; Iwata, Yoshio
概要:
The magnetorheological elastomer (MRE) is known to belong to a class of smart materials whose elastic properties can be
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varied by an externally applied magnetic field. In addition to the property of the field-dependent stiffness change of the MRE, the electrical resistance of the composite is also changed by the induced strain, thereby providing a new self-sensing feature. In the present study, a novel, dynamic vibration absorber is developed using an MRE with a self-sensing function and adaptability. The natural frequency of the absorber is instantaneously tuned to a dominant frequency extracted from the strain signal of MRE. The damping performance test shows that the vibration of a system with one degree-of-freedom that is exposed to a nonstationary disturbance can be adequately reduced by the proposed frequency-tunable dynamic absorber without the use of external sensors. © 2016 Society for Experimental Mechanics<br />In Press / Embargo Period 12 months
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| 6.
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Komatsuzaki, Toshihiko ; Iwata, Yoshio
概要:
An elastomer composite with controllable stiffness, known as a magnetorheological elastomer (MRE), is used in a dynamic
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vibration absorber whose natural frequency is tuned adaptively to the disturbance frequency through the application of an external magnetic field. The field-dependent property test of the fabricated MRE sample shows that the stiffness changes by more than six times compared to the baseline property value at a 40% iron powder volume concentration. The MRE is then used to fabricate a frequency-tunable dynamic absorber for mitigating transient vibrations of a one-degree-of-freedom system. Investigations show that the proposed absorber outperforms a conventional passive-type absorber throughout the tunable frequency range. © 2015 Toshihiko Komatsuzaki and Yoshio Iwata.
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| 7.
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Komatsuzaki, Toshihiko ; Iwata, Yoshio
概要:
A particle impact damper is a vibration absorber type that consists of a container attached to a primary vibrating struc
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ture. It also contains many particles that are constrained to move inside the container, whereby the damping effect can be obtained by collision between particles and the container. The discrete element method (DEM) has been developed for modeling granular systems, where the kinematics of each particle are calculated numerically using the equations of motion. However, the computational time is significant since the algorithm checks for particle contacts for all possible particle combinations. The use of a cellular automata (CA) modeling technique may provide increased computational efficiency due to the local updating of variables, and the discrete treatment of time and space. In this study, we propose a new approach combining DEM with CA for modeling a granular damper under a forced excitation. We use DEM to describe the particle motion according to the equations of motion, while CA is introduced for the particle contact checks in discrete space. We also investigate the effect of simplification in the contact force model, which allows the unit time step of numerical integration to become larger than that used in the strict model. It is shown that the suggested particle contact scanning method and the force approximation model contribute to the reduction of the computational time, and neither degenerates the calculation accuracy nor causes the numerical instability. © 2016 Springer Science+Business Media Dordrecht<br />Embargo Period 12 months
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| 8.
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Asanuma, Haruhiko ; Okubo, H. ; Komatsuzaki, Toshihiko ; Iwata, Yoshio
概要:
To downsize the clamp area and increase the output power of the harvester, we developed a miniature piezoelectric vibrat
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ion energy harvester with combining a Z-shaped folded spring and a mechanically-switching SSHI (synchronized switch harvesting on inductor). The overall harvester size is 4i×2i×3 cm3. The FEM analysis revealed that the output power increases and the value of the 1st and 2nd resonance frequencies move closer as the angle of the Z-shaped spring decreases, therefore, the smaller angle would be more promising. The experimental results showed that the maximum output power of our harvester for the 1st (20.2 Hz) and 2nd (53.0 Hz) resonance frequencies at the applied acceleration of 4.9 m/s2 are 088 and 0.98 mW, respectively. The reason for a marked enhancement of the output power for the 2nd resonance frequency is attributed to the vertical movement of the 2nd vibrational mode which applies larger mechanical stress to the piezo ceramic and achieves better electrical contact between the tip of the Z-shaped spring and the spring plunger. © Published under licence by IOP Publishing Ltd.
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| 9.
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Komatsuzaki, Toshihiko ; Han, Jing ; Uchida, Hiroaki
概要:
The sound quality of consumer products has recently become an important feature, receiving much attention in the fields
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of engineering and manufacturing. The sound could add value to the product in the way that it meets the interests and preferences of consumers in a wide range of fields. The present study deals with the sound emitted from beverage cans when lifting the tab of the can end to open it before drinking. With a view toward finding the characteristics of sound that have a sense of ease and certainty for the consumer when opening a beverage can, we introduce the semantic differential method for the subjective assessment of sounds of various cans. We then perform waveform analyses in both time and frequency domains to determine the physical properties of the desirable sounds. Finally, we successfully correlate the texture factor with the duration of the tearing sound, which may be a new way to design cans with pleasant sounds. © 2015 Elsevier Ltd. All rights reserved.
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| 10.
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Komatsuzaki, Toshihiko ; Sato, Hidenori ; Iwata, Yoshio ; Morishita, Shin
概要:
金沢大学工学部
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